Features All Tube design using 12AT7 dual triode. (Previous versions used 6072 or 12AX7.) Sensitivity: 17mV/Pa Noise: typically -120 dB EIN Max SPL: 150dB Actual output impedance 200 Ohms Description Product Description The MANLEY GOLD REFERENCE MULTI-PATTERN MICROPHONES are a statement, quite simply, of the finest microphones that money can buy in the pursuit of truly accurate musical recordings. The Gold Reference Series employ our own design of large capsules (1.25 inch overall, 1 inch diaphragm diameter) which are executed to precise tolerances made possible by modern micro-milling machinery available today in California. The capsule rings and back-plates are milled from solid brass. The gold diaphragm film comes from Germany and is tensioned using proprietary techniques by David Josephson ensuring capsule-to-capsule constancy, combined with the speed, "air", and superb ultra-high frequency response you have only dreamt about.